Acoustic diaphragm



NOV. 13, 1934. r A THOMAS 1,980,235

ACOUSTIC DIAPHRAGM Original Filed April- 4, 1929 In bar zwzwwf Patented Nov.) i3, @3 2;

UNITED Original application April 4, 1929, Serial No. 352,396. Divided and this application July 20, 1832, Serial No. 823,555. Renewed August 24,

I cum. (Cl. 181-32) My invention relates to the art of sound-transmittingand reproducing devices. and its obiect is to provide a vibratory diaphragm of novel structure capable of use in any kind of telephone '5 transmitter and receiver. Broadly stated, my new diaphragm is made of a ferro-nickel alloy substantially unaffected by variations in temperature, whereby the diaphragm retains its ori inalform or degree of tension without regard 10 to climatic changes.

The single figure in the accompanying drawing is a face view of an acoustic diaphragm constructed in accordance with my invention. For convenience I have shown a circular membrane 10 mounted for vibratory movement in a frame "12. The membrane 10 is a thin disk of Invar or similar term-nickel alloy, and it is preferably supported under tension sumciently high for pr per operation. Invar" is an alloy of apgo proximately 37% nickel and 63% iron. and it is not ailected by changes in temperature, so that the original tension of the diaphragm is preserved 1 Pm'thermore.

inailclimatesand min s Invar" is not liable to rust. When I describe by diaphragm as made of Invar or its equivalent, I do not mean that it must be composed entirely of that material, but substantially so.

The shape and size of diaphragm 10 are imto material in the broad aspect of my invention, for they can be varied for the best results in any particular design of instrument, whether for receiving or transmitting sound. No operating means for the diaphragm is shown, because this as invention is for the diaphragm itself, without regard to the other elements that go to make up a completetransmitter or receiver. My new diaphragm is especially useful for loudspeakers.

This case is a division of my pending application Serial Number 352,396, filed April 4, 1929.

I claim as my invention:

An acoustic diaphragm substantially composed of an alloy comprising approximately 37% nickel and 83% iron, whereby said diaphragm is substantially unaffected by changes in temperature.

ADOLPH A. THOMAS. 

